Methods for forming a transition metal niobium nitride film on a substrate by atomic layer deposition and related semiconductor device structures

ABSTRACT

Methods for forming a transition metal niobium nitride film on a substrate by atomic layer deposition and related semiconductor device structures are provided. In some embodiments methods may include contacting a substrate with a first reactant comprising a transition metal precursor, contacting the substrate with a second reactant comprising a niobium precursor and contacting the substrate with a third reactant comprising a nitrogen precursor. In some embodiments related semiconductor device structures may include a semiconductor body and an electrode comprising a transition metal niobium nitride disposed over the semiconductor body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of, and claims priority to and the benefit of, U.S. patent application Ser. No. 15/795,056, filed Oct. 26, 2017 and entitled “METHODS FOR FORMING A TRANSITION METAL NIOBIUM NITRIDE FILM ON A SUBSTRATE BY ATOMIC LAYER DEPOSITION AND RELATED SEMICONDUCTOR DEVICE STRUCTURES,” which claims priority to U.S. Provisional Patent Application Ser. No. 62/415,828, filed Nov. 1, 2016, the disclosures of which are hereby incorporated by reference herein.

BACKGROUND Field of the Invention

The present disclosure relates generally to methods for forming a transition metal niobium nitride film on a substrate by atomic layer deposition and related semiconductor device structures.

Description of the Related Art

Metal-oxide-semiconductor (MOS) technology has conventionally utilized n-type doped polysilicon as the gate electrode material. However, doped polysilicon may not be an ideal gate electrode material for advanced node applications. For example, although doped polysilicon is conductive, there may still be a surface region which can be depleted of carriers under bias conditions. This region may appear as an extra gate insulator thickness, commonly referred to as gate depletion, and may contribute to the equivalent oxide thickness. While the gate depletion region may be thin, on the order of a few angstroms (A), it may become significant as the gate oxide thicknesses are reduced in advance node applications. As a further example, polysilicon does not exhibit an ideal effective work function (eWF) for both NMOS and PMOS devices. To overcome the non-ideal effective work function of doped polysilicon, a threshold voltage adjustment implantation may be utilized. However, as device geometries reduce in advanced node applications, the threshold voltage adjustment implantation processes may become increasingly complex and impractical.

To overcome the problems associated with doped polysilicon gate electrodes, the non-ideal doped polysilicon gate material may be replaced with an alternative material, such as, for example, a transition metal nitride. For example, a transition metal nitride may be utilized to provide a gate electrode structure with a more ideal effective work function for both the NMOS and PMOS devices, where the effective work function of the gate electrode structure, i.e., the energy needed to extract an electron, must be compatible with the barrier height of the semiconductor material. For example, in the case of PMOS devices, the required effective work function is approximately 5.0 eV.

In addition, memory cell size has continuously decreased as the design rule of dynamic random access memory (DRAM) has decreased. Accordingly, the height of a capacitor, associated with the DRAM, has continuously increased and the thickness has become smaller in order to maintain a desired charge capacitance. The height of the capacitor has increased and the thickness of the capacitor has decreased because the charge capacitance is proportionate to the surface area of an electrode and the dielectric constant of a dielectric layer, and is inversely proportionate to the distance between the electrodes, i.e., the thickness of the dielectric layer. The high aspect ratio of the capacitor may cause “leaning” and this “leaning” may be variable according to the properties and/or thickness of the electrode comprising the capacitor. For example, DRAM capacitors comprising titanium nitride as an electrode material may lean when the aspect ratio of the capacitor is greater than approximately 15:1. Therefore alternative materials may be desirable for the DRAM capacitor electrodes to prevent leaning of arrays of capacitors (storage nodes) and the associated device failure resulting from leaning device structures.

Atomic layer deposition (ALD) may be utilized for the deposition of transition metal nitride films, such as, for example, tantalum nitride (TaN), titanium nitride (TiN), tungsten nitride (WN) and niobium nitride (NbN). However, the electronic, crystallographic and physical properties of known ALD transition metal nitride films may be limited and novel ALD transition metal nitride films may be desirable.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

In some embodiments, methods for forming a transition metal niobium nitride film on a substrate by atomic layer deposition are provided. The methods may comprise contacting the substrate with a first reactant comprising a transition metal precursor, contacting the substrate with a second reactant comprising a niobium precursor, and contacting the substrate with a third reactant comprising a nitrogen precursor.

In some embodiments, semiconductor device structures are provided. The semiconductor device structures may comprise a semiconductor body and an electrode comprising a transition metal niobium nitride disposed over the semiconductor body.

For the purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example of a process for forming a transition metal niobium nitride according to the embodiments of the disclosure;

FIG. 2 illustrates an example of a process for forming a transition metal niobium nitride according to additional embodiments of the disclosure;

FIG. 3 schematically illustrates a semiconductor device structure comprising a PMOS transistor according to the embodiments of the disclosure;

FIG. 4 schematically illustrates a semiconductor device structure comprising a DRAM capacitor according to embodiments of the disclosure;

FIG. 5 schematically illustrates a partially fabricated semiconductor device structure comprising transition metal niobium nitride layers deposited according to the embodiments of the disclosure;

FIG. 6 schematically illustrates a reaction system configured to perform the embodiments of the disclosure.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be an actual view of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “atomic layer deposition” (ALD) may refer to a vapor deposition process in which deposition cycles, preferably a plurality of consecutive deposition cycles, are conducted in a process chamber. Typically, during each cycle the precursor is chemisorbed to a deposition surface (e.g., a substrate surface or a previously deposited underlying surface such as material from a previous ALD cycle), forming a monolayer or sub-monolayer that does not readily react with additional precursor (i.e., a self-limiting reaction). Thereafter, if necessary, a reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the process chamber for use in converting the chemisorbed precursor to the desired material on the deposition surface. Typically, this reactant is capable of further reaction with the precursor. Further, purging steps may also be utilized during each cycle to remove excess precursor from the process chamber and/or remove excess reactant and/or reaction byproducts from the process chamber after conversion of the chemisorbed precursor. Further, the term “atomic layer deposition,” as used herein, is also meant to include processes designated by related terms such as, “chemical vapor atomic layer deposition”, “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy when performed with alternating pulses of precursor composition(s), reactive gas, and purge (e.g., inert carrier) gas.

As used herein, the term “substrate” may refer to any underlying material or materials that may be used, or upon which a device, a circuit or a film may be formed.

The present disclosure includes methods and device structures that may be used to form a transition metal niobium nitride film or comprise a transition metal niobium nitride film. The existing ALD transition metal nitride films may have limitations due to their inability to tune certain characteristics of the ALD transition metal nitride film; such characteristics may comprise the effective work function, the electrical resistivity, the density, and the Young's modulus.

For example, it is known that the effective work function of a gate electrode structure may vary as a function of its thickness, i.e., the effective work function of the gate electrode structure may decrease or increase with decreasing thickness of the materials comprising the gate electrode. As device geometries decrease in advanced node applications, the thickness of the corresponding device films, for example, such as the gate electrode, may also decrease with a corresponding change in the effective work function of the film. Such a change in the effective work function of the gate electrode at reduced thickness may result in a non-ideal effective work function for NMOS and PMOS device structures. In addition, it also known that the properties of the conductive materials comprising common DRAM capacitor electrodes may be non-ideal in terms of mechanical strength and oxidation resistance. Methods and structures are therefore required to provide a more desirable transition metal nitride film. Examples of such methods and structures are disclosed in further detail below.

ALD is based on typically self-limiting reactions, whereby sequential and alternating pulses of reactants are used to deposit about one atomic (or molecular) monolayer of material per deposition cycle. The deposition conditions and precursors are typically selected to provide self-saturating reactions, such that an adsorbed layer of one reactant leaves a surface termination that is non-reactive with the gas phase reactants of the same reactant. The substrate is subsequently contacted with a different reactant that reacts with the previous termination to enable continued deposition. Thus, each cycle of alternated pulses typically leaves no more than about one monolayer of the desired material. However, as mentioned above, the skilled artisan will recognize that in one or more ALD cycles more than one monolayer of material may be deposited, for example if some gas phase reactions occur despite the alternating nature of the process.

In some embodiments of the disclosure, an ALD-type process for depositing transition metal niobium nitride films may be illustrated with reference to FIG. 1 which illustrates non-limiting example ALD-type process 100. After initial surface termination, if necessary or desired, the ALD pulse sequence may begin at step 102. The ALD-type process 100 may then proceed with at least one deposition cycle which may comprise, contacting the substrate with a first reactant 104, contacting the substrate with a second reactant 106 and contacting the substrate with a third reactant 108. Once the first, second and third reactants have been exposed to the substrate the deposition cycle may be repeated 108 until a predetermined thickness of transition metal niobium nitride is achieved 110. When the desired predetermined thickness of transition metal niobium nitride is achieved the deposition cycle is terminated and the process may exit 112.

In some embodiments the ALD-type process 100 for depositing transition metal niobium nitride, may comprise at least one deposition cycle wherein the at least one deposition cycle may comprise, exposing the substrate to the first reactant, removing any unreacted first reactant and reaction by products from the reaction space, exposing the substrate to the second reactant, followed by a second removal step, and exposing the substrate to the third reactant, followed by a third removal step.

In some embodiments the ALD-type process 100 for depositing transition metal niobium nitride, may comprise at least one deposition cycle wherein the at least one deposition cycle may comprise, exposing the substrate to the first reactant, exposing the substrate to the second reactant, removing any unreacted first reactant and second reactant and reaction by products, and exposing the substrate to the third reactant, followed by a second removal step.

In some embodiments the ALD-type process for depositing transition metal niobium nitride, may comprise at least one deposition cycle wherein the at least one deposition cycle may comprise, exposing the substrate to the second reactant, removing any unreacted second reactant and reaction by products from the reaction space, exposing the substrate to a first reactant, followed by a second removal step, and exposing the substrate to the third reactant, followed by a third removal step.

In addition, it should be appreciated that in some embodiments, each contacting step may be repeated one or more times prior to advancing on to the subsequent processing step, i.e., prior to the subsequent contacting step or removal/purge step.

In some embodiments, the first reactant may comprise a metal precursor, in particular a transition metal precursor. The transition metal precursor or compound may comprise at least one of the transition metals selected from the group comprising, scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd) and mercury (Hg).

As a non-limiting example embodiment, a transition metal halide reactant, such as, e.g., titanium tetrachloride (TiCl₄), may be used as the transition metal precursor in ALD processes.

In some embodiments, the second reactant may comprise a niobium precursor and in some embodiments methods may comprise selecting the niobium precursor to comprise at least one of niobium pentachloride (NbCl₅), niobium pentafluoride (NbF₅), niobium pentaboride (NbB₅), niobium pentaiodide (NbI₅) and niobium pentabromide (NbBr₅).

In some embodiments, the third reactant may comprise a nitrogen precursor and in some embodiments methods may comprise selecting the nitrogen precursor to comprise at least one of ammonia (NH₃), ammonia salts, hydrogen azide (HN₃), alkyl derivatives of hydrogen azide, hydrazine (N₂H₄), hydrazine salts, alkyl derivatives of hydrazine, nitrogen fluoride (NF₃), and plasma-excited species of nitrogen (N₂).

Precursors may be separated by inert gases, such as argon (Ar) or nitrogen (N₂), to prevent gas-phase reactions between reactants and enable self-saturating surface reactions. In some embodiments, however, the substrate may be moved to separately contact a first transition metal reactant, a second niobium reactant and a third nitrogen reactant. Because the reactions self-saturate, strict temperature control of the substrates and precise dosage control of the precursors is not usually required. However, the substrate temperature may be such that an incident gas species does not condense into monolayers nor decompose on the surface. Surplus chemicals and reaction byproducts, if any, are removed from the substrate surface, such as by purging the reaction space or by moving the substrate, before the substrate is contacted with the next reactive chemical. Undesired gaseous molecules can be effectively expelled from a reaction space with the help of an inert purging gas. A vacuum pump may be used to assist in the purging.

According to some embodiments, ALD-type processes are used to form transition metal niobium nitride films, for example, titanium niobium nitride films on a substrate, such as an integrated circuit workpiece. Each ALD cycle may comprise three distinct deposition steps or phases. In a first phase of the deposition cycle (“the transition metal phase”), the substrate surface on which deposition is desired is contacted with a first reactant comprising a transition metal such as titanium (i.e., titanium source material or chemical) which chemisorbs onto the substrate surface, forming no more than about one monolayer of reactant species on the surface of the substrate.

In some embodiments, the transition metal (e.g., titanium) source chemical, also referred to herein as the “transition metal compound” (or in some embodiments as the “titanium compound”), is a halide and the adsorbed monolayer is terminated with halogen ligands. In some embodiments, the titanium halide may be titanium tetrachloride (TiCl₄).

In some embodiments, excess transition metal (e.g., titanium, tantalum or tungsten) source material and reaction byproducts (if any) may be removed from the substrate surface, e.g., by purging with an inert gas. Excess transition metal source material and any reaction byproducts may be removed with the aid of a vacuum generated by a pumping system.

In a second phase of the deposition cycle (“the niobium phase”), the substrate is contacted with a niobium precursor. In some embodiments the niobium precursor may comprise at least one of niobium pentachloride (NbCl₅), niobium pentafluoride (NbF₅), niobium pentaboride (NbB₅), niobium pentaiodide (NbI₅) and niobium pentabromide (NbBr₅).

The second niobium reactant may absorb on the substrate surface by either insertion or displacement of the titanium-containing molecules left on the substrate surface. The substrate surface therefore comprises a mixture of metal-containing molecules left on the substrate surface, the substrate surface comprising a mixture of transition metal species (e.g., titanium) and niobium species.

In some embodiments, excess second source chemical and reaction byproducts, if any, are removed from the substrate surface, for example by a purging gas pulse and/or vacuum generated by a pumping system. Purging gas is preferably any inert gas, such as, without limitation, argon (Ar), nitrogen (N₂) or helium (He). A phase is generally considered to immediately follow another phase if a purge (i.e., purging gas pulse) or other reactant removal step intervenes.

In a third phase of the deposition cycle (“the nitrogen phase”), the substrate is contacted with a nitrogen precursor. In some embodiments the nitrogen precursor may comprise at least one of ammonia (NH₃), ammonia salts, hydrogen azide (HN₃), alkyl derivatives of hydrogen azide, hydrazine (N₂H₄), hydrazine salts, alkyl derivatives of hydrazine (e.g., tertbutylhydrazine (C₄H₉N₂H₃), methylhydrazine (CH₃NHNH₂), dimethylhydrazine ((CH₃)₂N₂H₂)) nitrogen fluoride (NF₃) and plasma-excited species of nitrogen (N₂).

The third reactant, comprising a nitrogen precursor, may react with the titanium and niobium containing molecules left on the substrate surface. Preferably, in the third phase nitrogen is incorporated into the film by the interaction of the third nitrogen containing reactant with the monolayer left by the transition metal (e.g., titanium) source material and the niobium source material. In some embodiments, reaction between the third nitrogen containing precursors and the chemisorbed transition metal and niobium species produces a transition metal niobium nitride thin film over the substrate.

In some embodiments, excess third source chemical and reaction byproducts, if any, are removed from the substrate surface, for example by a purging gas pulse and/or vacuum generated by a pumping system. Purging gas may be any inert gas, such as, without limitation, argon (Ar), nitrogen (N₂) or helium (He). A phase is generally considered to immediately follow another phase if a purge (i.e., purging gas pulse) or other reactant removal step intervenes.

In some embodiments, the ALD-process of process 100 may comprise a plasma enhanced atomic layer deposition (PEALD) process. In such embodiments the third reactant may comprise a nitrogen precursor and may further comprise a plasma excited species of nitrogen (N₂). In some embodiments, the thirds reactant may comprise a nitrogen precursor and may further comprise a plasma excited species of any reactant including a nitrogen component. In some embodiments the third reactant, e.g., a plasma excited species of nitrogen (N₂), may be supplied to the substrate with the addition of further plasma excited species, such as plasma excited species of hydrogen (H₂).

In embodiments wherein the ALD-process comprises a plasma enhanced atomic layer deposition process utilizing plasma excited species, the substrate temperature during deposition may comprise a temperature of between approximately 250° C. and approximately 400° C. In embodiments where in the ALD-process comprises a thermal atomic layer deposition process, i.e., an absence of plasma excited species, the substrate temperature during deposition may comprise a temperature of between approximately 350° C. and approximately 450° C.

In some embodiments, a transition metal niobium nitride film formed according to one or more processes described herein is not a nanolaminate film. That is, separate and distinct layers may not be visible within the transition metal niobium nitride film. For example, a continuous or substantially continuous transition metal niobium nitride film may be formed.

The deposition rate of the thin film by ALD, which is typically presented as Å/pulsing cycle, depends on a number of factors including, for example, on the number of available reactive surface sites or active sites on the surface and bulkiness of the chemisorbing molecules. In some embodiments, the deposition rate of such films may range from about 0.3 to about 5.0 Å/pulsing cycle. In some embodiments, the deposition rate can be about 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 Å/pulsing cycle.

In some embodiments of the disclosure, an ALD-type process for depositing transition metal niobium nitride films may be illustrated with reference to FIG. 2 which illustrates non-limiting example process 200. After initial surface termination, if necessary or desired, the ALD pulse sequence may begin at step 202. The ALD-type process 200 may then proceed with at least one complete deposition cycle 203.

In some embodiments, a process of depositing a transition metal niobium nitride film comprises both a deposition process for depositing a transition metal nitride component (e.g., a number of deposition cycles for depositing a transition metal nitride, such as a number of transition metal nitride sub-cycles), and a deposition process for adding a niobium component to the growing film (e.g., a number of deposition cycles which includes a precursor comprising niobium, such as a number of niobium nitride sub-cycles). For example, a process for fabricating a transition metal niobium nitride film may include a number of complete deposition cycles, each complete deposition cycle including a number of transition metal nitride sub-cycles and a number of niobium nitride sub-cycles.

In some embodiments, a process of fabricating a transition metal niobium nitride film having desired characteristics can include a number of complete deposition cycles, where each complete deposition cycle includes a ratio of a number of transition metal nitride sub-cycles to a number of niobium nitride sub-cycles optimized to obtain the desired characteristics, such as, for example, Young's modulus, density, stoichiometry, electrical resistivity and crystallographic orientation. The ratio of the number of transition metal nitride sub-cycles to the number of niobium nitride sub-cycles of a complete deposition cycle can be expressed as having a percentage of niobium nitride sub-cycles (e.g., a niobium nitride sub-cycle percentage or a niobium nitride deposition sub-cycle percentage). For example, a complete deposition cycle for depositing a transition metal niobium nitride film including one deposition cycle for depositing a transition metal nitride component (e.g., one transition metal nitride sub-cycle) and four deposition cycles for adding a niobium component (e.g., four niobium nitride sub-cycles) can have a niobium nitride sub-cycle percentage of about 80%. In some embodiments, a complete deposition cycle can have a niobium nitride sub-cycle percentage of about 10% to about 100%, including about 25% to about 98%, about 50% to about 95%, and about 75% to about 85%.

In some embodiments, one or more parameters of a transition metal nitride sub-cycle can be different from that of another transition metal nitride sub-cycle. In some embodiments, one or more parameters of a transition metal nitride sub-cycle can be similar to or the same as that of another transition metal nitride sub-cycle such that the transition metal nitride sub-cycles are performed under similar or identical process conditions.

In some embodiments, one or more parameters of a niobium nitride sub-cycle can be different from that of another niobium nitride sub-cycle. In some embodiments, one or more parameters of a niobium nitride sub-cycle can be similar to or the same as that of another niobium nitride sub-cycle such that the niobium nitride sub-cycles are performed under similar or even identical process conditions.

In some embodiments, a transition metal niobium nitride film formed according to one or more processes described herein is a nanolaminate film. That is, separate and distinct layers may be visible within the transition metal niobium nitride film. For example, the transition metal niobium nitride film may comprise a nanolaminate and may further comprise at least one layer of a transition metal nitride and at least one layer of a niobium nitride.

In some embodiments, a transition metal niobium nitride film formed according to one or more processes described herein is not a nanolaminate film. That is, separate and distinct layers may not be visible within the transition metal niobium nitride film. For example, a continuous or substantially continuous transition metal niobium nitride film may be formed.

As described above, in some embodiments, a process for forming a transition metal niobium nitride film of a desired thickness and/or composition can include an ALD deposition process (e.g., a transition metal nitride deposition sub-cycle and/or a niobium nitride deposition sub-cycle can comprise an ALD process). ALD type processes are based on controlled surface reactions that are typically self-limiting. Gas phase reactions are avoided by contacting the substrate alternately and sequentially with precursors, although in some instances, some overlap is possible. Vapor phase precursors are separated from each other in the reaction chamber, for example, by removing excess precursors and/or precursor byproducts from the reaction chamber between precursor pulses. For example, an ALD deposition process can include contacting a substrate with a first reactant (e.g., a transition metal precursor for a transition metal nitride deposition sub-cycle) and a second reactant comprising niobium for a niobium nitride deposition sub-cycle such that the first and/or the second reactant adsorbs onto the substrate surface, and contacting the substrate with a third reactant (e.g., a nitrogen precursor of a transition metal nitride deposition sub-cycle or a nitrogen precursor of a niobium nitride deposition sub-cycle). Exposure of the substrate to the first precursor, the second precursor and the third precursor may be repeated as many times as required to achieve a film of a desired thickness and composition. Excess precursors may be removed from the vicinity of the substrate, for example by evacuating the reaction chamber and/or purging from the reaction space with an inert gas, after each contacting step. For example, excess reactants and/or reaction byproducts may be removed from the reactor chamber between precursor pulses by drawing a vacuum on the reaction chamber to evacuate excess reactants and/or reaction byproducts. In some embodiments, the reaction chamber may be purged between precursor pulses. The flow rate and time of each precursor, is tunable, as is the purge step, allowing for control of the dopant concentration and depth profile in the film.

Each cycle of an ALD process can include at least two distinct processes or phases. The provision and removal of a precursor from the reaction space may be considered a phase. In a first process or phase of an ALD process, of a transition metal nitride deposition sub-cycle, for example, a first precursor comprising a transition metal is provided and forms no more than about one monolayer on the substrate surface. This precursor is also referred to herein as “the transition metal precursor” or “transition metal reactant.” In a second process or phase of the ALD process of a transition metal nitride deposition sub-cycle, for example, a third precursor comprising a nitrogen-containing compound is provided and reacts with the adsorbed transition metal precursor to form a transition metal nitride. This third precursor may also be referred to as a “nitrogen precursor” or “nitrogen reactant.” As described herein, the third precursor may comprise ammonia (NH₃) and/or another suitable nitrogen-containing compound that is able to react with the adsorbed first reactant under the process conditions. Preferably the reaction leaves a termination that is further reactive with the first precursor or another precursor for a different phase.

Additional processes or phases may be added and phases may be removed as desired to adjust the composition of the final transition metal niobium nitride film. In some embodiments, the additional processes or phases can include one or more precursors different from that of the first and second process or phase. For example, one or more additional precursors can be provided in the additional processes or phases. In some embodiments, the additional processes or phases can have similar or identical process conditions as that of the first and second process or phase. In some embodiments, for a transition metal nitride deposition sub-cycle, one or more deposition sub-cycles typically begins with provision of the transition metal precursor followed by the nitrogen precursor. In some embodiments, one or more deposition sub-cycles begins with provision of the nitrogen precursor followed by the transition metal precursor. One or more of the precursors may be provided with the aid of a carrier gas, such as nitrogen (N₂), argon (Ar) and/or helium (He). In some embodiments, the carrier gas may comprise another inert gas.

In some embodiments, in a first process or phase of an ALD process of a niobium nitride deposition sub-cycle, for example, a second precursor comprising niobium is provided and forms no more than about one monolayer on the substrate surface. This precursor is also referred to herein as “the precursor comprising niobium” or “the reactant comprising niobium.” In a second process or phase of the ALD process of a niobium nitride deposition sub-cycle, for example, a third precursor comprising a nitrogen-containing compound is provided and reacts with the adsorbed precursor comprising the niobium to form a niobium nitride, thereby introducing niobium into the transition metal nitride film. This third precursor may also be referred to as a “nitrogen precursor” or “nitrogen reactant.” As described herein, the third precursor may comprise ammonia (NH₃) and/or another suitable nitrogen-containing compound or nitrogen excited species. The nitrogen precursor of the niobium nitride deposition sub-cycle may be the same as or different from a nitrogen precursor of the transition metal nitride deposition sub-cycle.

Additional processes or phases may be added and phases may be removed as desired to adjust the composition of the final film. In some embodiments for depositing a transition metal niobium nitride film, one or more niobium nitride deposition sub-cycles typically begins with provision of the precursor comprising the niobium followed by the nitrogen precursor. In some embodiments, one or more deposition sub-cycles begins with provision of the nitrogen precursor followed by the precursor comprising the niobium. One or more of the precursors of the niobium nitride sub-cycle may be provided with the aid of a carrier gas, such as nitrogen (N₂), Ar and/or He. In some embodiments, the carrier gas may comprise another inert gas.

FIG. 2 shows a flow chart of an example of a process 200 for forming a transition metal niobium nitride film on a substrate. In some embodiments the process is a thermal ALD process, whereas in other embodiments the process is a plasma enhanced ALD process. The ALD-process 200 can include a complete deposition cycle 203 having a transition metal nitride sub-cycle 204. As shown in FIG. 2 , the ALD-process 200 can include a niobium nitride sub-cycle 206 for adding niobium components to the growing transition metal niobium nitride film. In some embodiments, the transition metal nitride sub-cycle 204, niobium nitride sub-cycle 206, and/or the complete deposition cycle 203 can be repeated a number of times to form a transition metal niobium nitride film having a desired composition and/or thickness. The ratio of the transition metal nitride sub-cycle 204 to the niobium nitride sub-cycle 206 can be varied to tune the concentration of niobium in the film and thus to achieve a film with desired characteristics. For example, the number of times niobium nitride sub-cycle 206 is repeated relative to the number of times the transition metal sub-cycle 204 is repeated can be selected to provide a transition metal nitride film with desired characteristics (e.g., desired electrical resistivity, density, and mechanical properties).

The transition metal nitride sub-cycle 204 can include blocks 208 and 210. In block 208, the substrate can be exposed to a first reactant which may comprise a transition metal precursor. In block 210, the substrate can be exposed to a third reactant which may comprise a nitrogen precursor. In some embodiments, the transition metal nitride sub-cycle 204 can be repeated a number of times (e.g., a number of repetitions of the blocks 208 followed by 210). In some embodiments, block 208 or block 210 can be repeated a number of times before performing one or more times the other block. For example, block 208 can be repeated a number of times before performing block 210.

In some embodiments pulses of the transition metal precursor for exposing the substrate to the transition metal precursor and pulses of nitrogen precursor for exposing the substrate to the nitrogen precursor are separated by a step of removing excess transition metal precursor from the reactor (not shown). In some embodiments excess nitrogen precursor is removed prior to repeating the transition metal nitride sub-cycle 204. In some embodiments, the transition metal nitride sub-cycle 204 is an ALD process. In some embodiments, the pulses of the transition metal and nitrogen precursor may at least partially overlap. In some embodiments, no additional precursors are provided to the reaction chamber either between blocks 208 and 210, or before starting blocks 208 and 210.

The niobium nitride sub-cycle 206 for introducing a niobium component into the transition metal nitride film can include blocks 212 and 214. In block 212, the substrate can be exposed to a second precursor comprising niobium. In block 214, the substrate can be exposed to a nitrogen precursor. In some embodiments, niobium nitride sub-cycle 206 can be repeated a number of times. In some embodiments, block 212 or block 214 can be repeated a number of times before performing one or more times the other block. For example, block 212 can be repeated a number of times before performing block 214.

In some embodiments excess nitrogen precursor is removed prior to repeating the niobium nitride sub-cycle 206. In some embodiments, excess precursor comprising the niobium from block 212 can be removed prior to exposing the substrate to the nitrogen precursor in block 214. In some embodiments, the niobium nitride sub-cycle 206 is an ALD process. In some embodiments, the pulses of the precursor comprising niobium and of the nitrogen precursor may at least partially overlap. In some embodiments, no additional precursors are provided to the reaction chamber either between blocks 212 and 214, or before starting blocks 212 and 214.

Once the at least one transition metal nitride sub-cycle and at least one niobium nitride sub-cycle have been performed the complete deposition cycle 203 may be repeated 216 until a predetermined thickness of transition metal niobium nitride is achieved 218. When the desired predetermined thickness of transition metal niobium nitride is achieved the complete deposition cycle is terminated and the process may exit 220.

In some embodiments, the transition metal nitride sub-cycle 204 may utilize a first reactant and the first reactant may comprise a metal precursor, in particular a transition metal precursor. The transition metal precursor or compound may comprise at least one of the transition metals selected from the group comprising, scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd) and mercury (Hg).

As a non-limiting example embodiment, a transition metal halide reactant, such as, e.g., titanium tetrachloride (TiCl₄), may be used as the transition metal precursor in the ALD processes described herein.

In some embodiments, the transition metal nitride sub-cycle 204 may utilize a third reactant and the third reactant may comprise a nitrogen precursor. Methods of the embodiments of the disclosure may comprise selecting the nitrogen precursor to comprise at least one of ammonia (NH₃), ammonia salts, hydrogen azide (HN₃), alkyl derivatives of hydrogen azide, hydrazine (N₂H₄), hydrazine salts, alkyl derivatives of hydrazine (e.g., tertbutylhydrazine (C₄H₉N₂H₃), methylhydrazine (CH₃NHNH₂), dimethylhydrazine ((CH₃)₂N₂H₂)), nitrogen fluoride (NF₃) and plasma-excited species of nitrogen (N₂).

In some embodiments, the niobium nitride sub-cycle 206 may utilize a second reactant and the second reactant may comprise a niobium precursor. Methods of the embodiments of the disclosure may comprise selecting the niobium precursor to comprise at least one of niobium pentachloride (NbCl₅), niobium pentafluoride (NbF₅), niobium pentaboride (NbB₅), niobium pentaiodide (NbI₅) and niobium pentabromide (NbBr₅).

In some embodiments, the niobium nitride sub-cycle 206 may utilize a third reactant and the third reactant may comprise a nitrogen precursor. Methods of the embodiments of the disclosure may comprise selecting the nitrogen precursor to comprise at least one of ammonia (NH₃), ammonia salts, hydrogen azide (HN₃), alkyl derivatives of hydrogen azide, hydrazine (N₂H₄), hydrazine salts, alkyl derivatives of hydrazine, nitrogen fluoride (NF₃) and plasma-excited species of nitrogen (N₂).

In some embodiments, the ALD-process of process 200 may comprise a plasma enhanced atomic layer deposition (PEALD) process. In such embodiments the nitrogen precursor may comprise a plasma excited species of nitrogen (N₂) or a plasma excited species of any nitrogen containing reactant. In some embodiments the third reactant, e.g., a plasma excited species of nitrogen (N₂), may be supplied to the substrate with the addition of further plasma excited species, such as plasma excited species of hydrogen (H₂).

In embodiments wherein the ALD-process 200 comprises a plasma enhanced atomic layer deposition process utilizing plasma excited species, the substrate temperature during deposition may comprise a temperature of between approximately 250° C. and approximately 400° C. In embodiments where in the ALD-process 200 comprises a thermal atomic layer deposition process, i.e., an absence of plasma excited species, the substrate temperature during deposition may comprise a temperature of between approximately 350° C. and approximately 450° C.

The deposition rate of the thin film by ALD, which is typically presented as Å/pulsing cycle, depends on a number of factors including, for example, on the number of available reactive surface sites or active sites on the surface and bulkiness of the chemisorbing molecules. In some embodiments, the deposition rate of such films may range from about 0.3 to about 5.0 Å/pulsing cycle. In some embodiments, the deposition rate can be about 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 Å/pulsing cycle.

In some embodiments of the disclosure the ALD processes described herein may be utilized for forming a transition metal niobium nitride film on a substrate. The transition metal niobium nitride film may comprise at least one of a transition metal selected from the group comprising, scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd) and mercury (Hg). In some embodiments, the transition metal niobium nitride may comprise at least one of a titanium niobium nitride, a tantalum niobium nitride and a tungsten niobium nitride.

In non-limiting example embodiments of the disclosure the transition metal niobium nitride may comprise a titanium niobium nitride. In some embodiments, methods may comprise forming the tin niobium nitride to have a Young's modulus of greater than approximately 390 gigapascals. In some embodiments, methods may comprise forming the titanium niobium nitride to have a density of greater than approximately 5.4 g/cm³. In some embodiments, methods may comprise forming the titanium niobium nitride to have an electrical resistivity of between approximately 200 μΩ-cm and approximately 1000 μΩ-cm.

In some embodiments of the disclosure, the transition metal niobium nitride may comprise a titanium niobium nitride and may have an as-deposited r.m.s. surface roughness (R_(a)) which is less than 8 Angstroms, or less than 6 Angstroms, or even less than 4 Angstroms. It has been found that the surface roughness of the as-deposited transition metal niobium nitride may reduce as the niobium nitride content in the film is decreased from 100%, therefore in some embodiments of the disclosure the methods may involve reducing the surface roughness of the transition metal niobium nitride by decreasing the niobium nitride content in the film. In some embodiments, of the disclosure it was found that the minimum in surface roughness of the transition metal niobium nitride may be found for a niobium nitride sub-cycle percentage of 50% which may correspond to a transition metal niobium nitride film with a surface roughness of less than 4 Angstroms.

The transition metal niobium nitride films, such as titanium niobium nitride films, formed by the ALD processes disclosed herein can be utilized in a variety of contexts. In one non-limiting example embodiment, the transition metal niobium nitride may be utilized in the formation of gate electrode structures. One of skill in the art will recognize that the processes described herein are applicable to many contexts, including fabrication of PMOS transistors including planar devices as well as multiple gate transistors, such as FinFETs. In another non-limiting example embodiment, the transition metal niobium nitride may be utilized as an electrode in a DRAM device structure. In another non-limiting example embodiment, the transition metal niobium nitride may be utilized as a barrier material and/or a capping layer in electrical interconnection applications.

As a non-limiting example, and with reference to FIG. 3 , a semiconductor device structure 300 may comprise a semiconductor body 316 and an electrode 310 comprising a transition metal niobium nitride disposed over the semiconductor body 316. In more detail, the semiconductor device structure may comprise a transistor structure and may also include a source region 302, a drain region 304, and a channel region 306 there between. A transistor gate structure 308 may comprise an electrode 310, i.e., a gate electrode, which may be separated from the channel region 306 by a gate dielectric 312. According to the teaching of the present disclosure, the gate electrode 310 may comprise a transition metal niobium nitride film, such as titanium niobium nitride, formed by an atomic layer deposition process as described herein. As shown in FIG. 3 , in some embodiment the transistor gate structure 308 may further comprise one or more additional conductive layers 314 formed on the gate electrode 310. The one or more additional conductive layers 314 may comprise at least one of polysilicon, a refractory metal, a transition metal carbide and a transition metal nitride.

In some embodiments, the semiconductor device structure 300 may comprise a PMOS transistor, the PMOS transistor may further comprise the transistor gate structure 308. The PMOS transistor gate structure 308 may comprise a gate electrode 310 comprising a transition metal niobium nitride film and a gate dielectric 312 disposed between the transition metal nitride film and a semiconductor body 316.

In some embodiments, the gate electrode 310, may comprise a transition metal niobium nitride film, such as, for example, titanium niobium nitride, tantalum niobium nitride, and tungsten niobium nitride. As a non-limiting example of the embodiments of the disclosure, the semiconductor device structure may comprise a silicon body 316, a hafnium oxide (2 nm) gate dielectric 312 and one of a titanium niobium nitride (niobium nitride sub-cycle percentage of 50%.), a niobium nitride, and a titanium nitride as the gate electrode 310. An additional conductive layer disposed on the gate electrode 310 may comprise platinum. Table 1 below shows the effective work function measured for the non-limiting examples for various thickness of the gate electrode 310. In some embodiments, the transistor gate structure 308 may comprise a titanium niobium nitride gate electrode and the transistor gate structure may have an effective work function of greater than approximately 4.6 eV, or greater than 4.7 eV, or even greater than 4.85 eV

TABLE 1 Gate Electrode TiNbN TiNbN NbN TiN Thickness (nm) 3 10 10 10 Effective work 4.60 4.85 4.78 4.80 function (eV)

It should be noted that the embodiments of the disclosure allow for formation of gate electrode structures comprising thin metal niobium nitrides films with increased effective work function, for example, in some embodiments methods may comprise forming a gate electrode structure comprising a transition metal niobium nitride gate electrode with a thickness of less than 100 Angstroms with an effective work function of greater than 4.85 eV. In further embodiments, methods may comprise forming the gate electrode structure comprising a transition metal niobium nitride gate electrode with a thickness of less than 30 Angstroms with an effective work function of greater than 4.6 eV.

As a non-limiting example, the transition metal niobium nitride film comprising the gate electrode 310 may in some embodiment have a thickness of less than 50 Angstroms, or in some embodiments less than 30 Angstroms or even in some embodiments less than 20 Angstroms.

In some embodiments of the disclosure, the gate electrode 310 may comprise a metallic bilayer including a first metallic layer of a transition metal niobium nitride and a second metallic layer, disposed over the first metallic layer at select MOS device locations by patterning and etching steps, the second metallic layer comprising, for example, a metal nitride. As a non-limiting example, the bilayer metallic gate electrode 310 may comprise a titanium niobium nitride film with a thickness of 10-30 Angstroms and an overlying, adjacent titanium nitride film with a thickness of 10-30 Angstroms. In some embodiments of the disclosure, the transition metal niobium nitride film may act as an etch stop to prevent over etching and protect the underlying gate dielectric. Therefore in some embodiments, the transition metal niobium nitride may have an etch selectivity, i.e., the relative etching rate of the overlying metal nitride film compared with the transition metal niobium nitride film, of greater than 2:1, or greater than 5:1, or even greater than 10:1. For example, the bilayer metallic gate electrode may be etched by a combination of wet etch chemistries (e.g., utilizing hydrofluoric acid) and dry etch chemistries (utilizing fluorine based etch chemistries). In some embodiments of the disclosure, the etch rate of the transition metal niobium nitride was found to increase with decreasing niobium nitride content, therefore the etch selectivity of the transition metal niobium nitride may be tailored for a specific application by tuning the composition of the transition metal niobium nitride. In some embodiments of the disclosure, the etching of the metallic bilayer gate electrode may be performed such that the thickness of the overlying metal nitride and/or the thickness of the transition metal niobium nitride varies across the surface of a substrate (or an integrated circuit). The variation in thickness of the bilayer metallic gate electrodes results in gate electrodes with different effective work functions which consequently may result in a plurality of MOS devices with varying threshold voltages, i.e., multi-V_(t) MOS devices in an integrated circuit.

As another non-limiting example embodiment, the transition metal niobium nitride may be utilized as an electrode in a DRAM device structure as illustrated in FIG. 4 . In more detail, FIG. 4 illustrates a semiconductor device structure 400 comprising a semiconductor body 402 and an electrode 404 comprising a transition metal niobium nitride disposed over the semiconductor body.

FIG. 4 illustrates a cross-section view of a partially fabricated DRAM device structures and the processes for forming such a DRAM device structure are described in U.S. Pat. No. 7,910,452 issued to Roh, et al., and incorporated by reference herein. Referring to FIG. 4 , an insulation layer 406 may be formed over a semiconductor body 402 which comprises a semi-finished substrate. Storage node contact holes are formed in the insulation layer 406 and storage node contact plugs 408 are formed in the storage node contact holes. The insulation layer 406 may comprise an undoped silicate glass (USG) and may be formed to a thickness ranging from approximately 1,000 Angstroms to approximately 3,000 Angstroms. A patterned etch stop layer 410 may be formed over the insulation layer 406. A conductive layer for forming the storage node may comprise an electrode 404 and the electrode 404 may comprise a transition metal niobium nitride and structurally may comprise a cylinder type storage node. In some embodiments, the electrode 404 may comprise at least one of a titanium niobium nitride, a tantalum niobium nitride and a tungsten niobium nitride.

In non-limiting example embodiments of the disclosure the electrode 404 may comprise a titanium niobium nitride. In some embodiments, methods may comprise forming the titanium niobium nitride to have a Young's modulus of greater than approximately 390 gigapascals. In some embodiments, methods may comprise forming the titanium niobium nitride to have a density of greater than approximately 5.4 g/cm³. In some embodiments, methods may comprise forming the titanium niobium nitride to have an electrical resistivity of less than approximately 1000 μΩ-cm.

As another non-limiting example embodiment, a transition metal niobium nitride may be utilized as a barrier material and/or a capping layer in a back-end-of-line (BEOL) metallization application, as illustrate in FIG. 5 . In more detail, FIG. 5 illustrates a partially fabricated semiconductor device structure 500 comprising, a substrate 502 which may comprise partially fabricated and/or fabricated semiconductor device structures such as transistors and memory elements (not shown). The partially fabricated semiconductor device structure 500 may include a dielectric material 504 formed over the substrate 502 which may comprise a low dielectric constant material, i.e., a low-k dielectric, such as a silicon containing dielectric or a metal oxide. A trench may be formed in the dielectric material 504 and a barrier material 506 may disposed on the surface of the trench which prevents, or substantially prevents, the diffusion the metal interconnect material 508 into the surrounding dielectric material 504. In some embodiments of the disclosure, the barrier material 506 may comprise a transition metal niobium nitride, such as, for example, a titanium niobium nitride. In some embodiments of the disclosure the transition metal niobium nitride may have a thickness of less than 35 Angstroms, or 25 Angstroms, or even 15 Angstroms. Not to be bound by any theory, but it is believed that a transition metal niobium nitride barrier material may be capable of preventing diffusion of the metal interconnect material 508 at a significantly lower thickness than common barrier materials utilized currently for the fabrication of integrated circuits. The partially fabricated semiconductor structure 500 may also comprise a metal interconnect material 508 for electrical interconnecting a plurality of device structures disposed in substrate 502. In some embodiments, the metal interconnect material 508 may comprise one or more of copper, or cobalt. In addition to the use of a transition metal niobium nitride as a barrier material, a transition metal niobium nitride may also be utilized as a capping layer. Therefore, with reference to FIG. 5 , the partially fabricated semiconductor device structure 500 may also include a capping layer 510 disposed directly on the upper surface of the metal interconnect material 508. The capping layer 510 may be utilized to prevent oxidation of the metal interconnect material 508 and importantly prevent the diffusion of the metal interconnect material 508 into additional dielectric materials formed over the partially fabricated semiconductor structure 500 in subsequent fabrication processes, i.e., for multi-level interconnect structures. In some embodiments of the disclosure, the capping layer 510 may also comprise a transition metal niobium nitride, such as, for example, titanium niobium nitride with a thickness of less than 20 Angstroms, or less than 15 Angstroms, or even less than 10 Angstroms. In some embodiments, the metal interconnect material 508, the barrier material 506, and the capping layer 510 may collectively form an electrode for the electrical interconnection of a plurality of semiconductor devices disposed in the substrate 502.

Embodiments of the disclosure may also include a reaction system configured to perform the methods of the disclosure. In more detail, FIG. 6 schematically illustrates a reaction system 600 including a reaction chamber 602 that further includes mechanism for retaining a substrate (not shown) under predetermined pressure, temperature, and ambient conditions, and for selectively exposing the substrate to various gases. A precursor reactant source 604 may be coupled by conduits or other appropriate means 604A to the reaction chamber 602, and may further couple to a manifold, valve control system, mass flow control system, or mechanism to control a gaseous precursor originating from the precursor reactant source 604. A precursor (not shown) supplied by the precursor reactant source 604, the reactant (not shown), may be liquid or solid under room temperature and standard atmospheric pressure conditions. Such a precursor may be vaporized within a reactant source vacuum vessel, which may be maintained at or above a vaporizing temperature within a precursor source chamber. In such embodiments, the vaporized precursor may be transported with a carrier gas (e.g., an inactive or inert gas) and then fed into the reaction chamber 602 through conduit 604A. In other embodiments, the precursor may be a vapor under standard conditions. In such embodiments, the precursor does not need to be vaporized and may not require a carrier gas. For example, in one embodiment the precursor may be stored in a gas cylinder. The reaction system 600 may also include additional precursor reactant sources, such precursor reactant sources 606 and 608 which may also be coupled to the reaction chamber by conduits 606A and 608A respectively, as described above.

A purge gas source 610 may also be coupled to the reaction chamber 602 via conduits 610A, and selectively supplies various inert or noble gases to the reaction chamber 602 to assist with the removal of precursor gas or waste gases from the reaction chamber. The various inert or noble gases that may be supplied may originate from a solid, liquid or stored gaseous form.

The reaction system 600 of FIG. 6 , may also comprise a system operation and control mechanism 612 that provides electronic circuitry and mechanical components to selectively operate valves, manifolds, pumps and other equipment included in the reaction system 600. Such circuitry and components operate to introduce precursors, purge gases from the respective precursor sources 604, 606, 608 and purge gas source 610. The system operation and control mechanism 612 also controls timing of gas pulse sequences, temperature of the substrate and reaction chamber, and pressure of the reaction chamber and various other operations necessary to provide proper operation of the reaction system 400. The operation and control mechanism 612 can include control software and electrically or pneumatically controlled valves to control flow of precursors, reactants and purge gases into and out of the reaction chamber 602. The control system can include modules such as a software or hardware component, e.g., a FPGA or ASIC, which performs certain tasks. A module can advantageously be configured to reside on the addressable storage medium of the control system and be configured to execute one or more processes.

In some embodiments, the reaction system 600 of FIG. 6 may comprise a plasma enhanced atomic layer deposition system and may additional comprise a plasma generation component which may in some embodiments be “local”, i.e., a component part of the reaction chamber 602, or alternative may in some embodiments be “remote”, i.e., the plasma and associated plasma excited species are generated remotely from the reaction chamber and subsequently feed to the reaction chamber utilizing appropriate conduits.

Those of skill in the relevant arts appreciate that other configurations of the present reaction system are possible, including different number and kind of precursor reactant sources and purge gas sources. Further, such persons will also appreciate that there are many arrangements of valves, conduits, precursor sources, purge gas sources that may be used to accomplish the goal of selectively feeding gasses into reaction chamber 602. Further, as a schematic representation of a reaction system, many components have been omitted for simplicity of illustration, and such components may include, for example, various valves, manifolds, purifiers, heaters, containers, vents, and/or bypasses.

The example embodiments of the disclosure described above do not limit the scope of the invention, since these embodiments are merely examples of the embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the disclosure, in addition to those shown and described herein, such as alternative useful combination of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims. 

What is claimed is:
 1. A method for forming a transition metal niobium nitride film on a substrate by atomic layer deposition, the method comprising: performing a deposition cycle, the deposition cycle comprising: contacting the substrate with a first reactant comprising a transition metal halide precursor, contacting the substrate with a second reactant comprising a niobium precursor to form a mixture of transition metal species and niobium species, contacting the substrate with a third reactant comprising a nitrogen precursor to react with the transition metal species and the niobium species to form a transition metal niobium nitride, and removing unreacted third reactant from a surface of the substrate prior to contacting with the first reactant; and repeating the deposition cycle until the transition metal niobium nitride film reaches a predetermined thickness, wherein contacting the substrate with the first reactant comprises flowing the first reactant for a first reactant pulse period, wherein contacting the substrate with the third reactant comprises flowing the third reactant for a third reactant pulse period, wherein the first reactant pulse period and the third reactant pulse period at least partially overlap in the deposition cycle.
 2. The method of claim 1, wherein the deposition cycle comprises sequentially contacting with the first reactant, the third reactant and the second reactant.
 3. The method of claim 2, wherein the deposition cycle is repeated two or more times and wherein a reaction with the third reactant leaves a termination on the substrate surface that is further reactive with the first reactant.
 4. The method of claim 1, wherein the transition metal halide comprises at least one of the transition metals selected from the group comprising, scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd) and mercury (Hg).
 5. The method of claim 1, wherein the second reactant is selected from the group consisting of niobium pentafluoride (NbF₅), niobium pentaboride (NbB₅), niobium pentaiodide (NbI₅) and niobium pentabromide (NbBr₅).
 6. The method of claim 1, further comprising selecting the transition metal halide precursor to comprise at least one of a titanium precursor, a tantalum precursor and a tungsten precursor.
 7. The method of claim 6, further comprising selecting the titanium precursor to comprise a titanium halide.
 8. The method of claim 7, further comprising selecting the titanium halide to comprise titanium tetrachloride (TiCl₄).
 9. The method of claim 1, further comprising selecting the niobium precursor to comprise at least one of niobium pentachloride (NbCl₅), niobium pentafluoride (NbF₅), niobium pentaboride (NbB₅), niobium pentaiodide (NbI₅) and niobium pentabromide (NbBr₅).
 10. The method of claim 1, further comprising selecting the nitrogen precursor to comprise at least one of ammonia (NH₃), ammonia salts, hydrogen azide (HN₃), alkyl derivatives of hydrogen azide, hydrazine (N₂H₄), hydrazine salts, alkyl derivatives of hydrazine, nitrogen fluoride (NF₃) and plasma-excited species of nitrogen (N₂).
 11. The method of claim 1, wherein contacting the substrate with the third reactant further comprises contacting the substrate with a plasma-excited species of hydrogen (H₂).
 12. The method of claim 1, wherein the method is a plasma-enhanced atomic layer deposition process.
 13. The method of claim 1, further comprising, heating the substrate to a temperature of between approximately 250° C. and approximately 450° C.
 14. The method of claim 1, further comprising forming the transition metal niobium nitride to have a Young's modulus of greater than approximately 390 gigapascals.
 15. The method of claim 1, further comprising: after contacting with the substrate with the second reactant, purging any unreacted second reactant, wherein the step of contacting the substrate with a third reactant is subsequent to the step of contacting the substrate with the first reactant.
 16. The method of claim 1, further comprising forming a gate electrode structure comprising a barrier layer comprising the transition metal niobium nitride and a capping layer comprising the transition metal niobium nitride.
 17. The method of claim 16, wherein the gate electrode structure comprises an effective work function greater than 4.6 eV.
 18. The method of claim 1, further comprising forming a dynamic random access (DRAM) capacitor comprising the transition metal niobium nitride.
 19. The method of claim 1, further comprising forming a barrier material comprising the transition metal niobium nitride.
 20. The method of claim 1, further comprising forming a capping layer comprising the transition metal niobium nitride.
 21. The method of claim 1, wherein an etching rate of an overlying metal nitride film to an etching rate of the transition metal niobium nitride film is greater than 10:1.
 22. The method of claim 1, wherein the transition metal niobium nitride has a r.m.s. surface roughness (R_(a)) of less than 4 Angstroms.
 23. A reaction system configured to perform the method of claim
 1. 